[Xen-devel] [PATCH] linux/x86: fix amd64-agp aperture validation

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

Under Xen, pfn_valid() on a machine address makes no sense. But even on
native, under CONFIG_DISCONTIGMEM, assuming that a !pfn_valid() implies
all subsequent pfn-s are also invalid is wrong. Thus replace this by
explicitly checking against the E820 map.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
Acked-by: Mark Langsdorf <mark.langsdorf@xxxxxxx>

Index: sle10sp1-2007-03-28/arch/i386/kernel/setup-xen.c
===================================================================
--- sle10sp1-2007-03-28.orig/arch/i386/kernel/setup-xen.c       2007-04-04 
17:07:13.000000000 +0200
+++ sle10sp1-2007-03-28/arch/i386/kernel/setup-xen.c    2007-04-04 
16:45:36.000000000 +0200
@@ -1022,6 +1022,35 @@ efi_memory_present_wrapper(unsigned long
        return 0;
 }
 
+/*
+ * This function checks if any part of the range <start,end> is mapped
+ * with type.
+ */
+int
+e820_any_mapped(u64 start, u64 end, unsigned type)
+{
+       int i;
+
+#ifndef CONFIG_XEN
+       for (i = 0; i < e820.nr_map; i++) {
+               const struct e820entry *ei = &e820.map[i];
+#else
+       if (!is_initial_xendomain())
+               return 0;
+       for (i = 0; i < machine_e820.nr_map; ++i) {
+               const struct e820entry *ei = &machine_e820.map[i];
+#endif
+
+               if (type && ei->type != type)
+                       continue;
+               if (ei->addr >= end || ei->addr + ei->size <= start)
+                       continue;
+               return 1;
+       }
+       return 0;
+}
+EXPORT_SYMBOL_GPL(e820_any_mapped);
+
  /*
   * This function checks if the entire range <start,end> is mapped with type.
   *
Index: sle10sp1-2007-03-28/arch/x86_64/kernel/e820-xen.c
===================================================================
--- sle10sp1-2007-03-28.orig/arch/x86_64/kernel/e820-xen.c      2007-04-04 
17:07:13.000000000 +0200
+++ sle10sp1-2007-03-28/arch/x86_64/kernel/e820-xen.c   2007-04-04 
17:07:28.000000000 +0200
@@ -97,17 +97,27 @@ static inline int bad_addr(unsigned long
        return 0;
 } 
 
-#ifndef CONFIG_XEN
 /*
  * This function checks if any part of the range <start,end> is mapped
  * with type.
  */
-int __meminit
+int
 e820_any_mapped(unsigned long start, unsigned long end, unsigned type)
 { 
        int i;
+
+#ifndef CONFIG_XEN
        for (i = 0; i < e820.nr_map; i++) { 
                struct e820entry *ei = &e820.map[i]; 
+#else
+       extern struct e820map machine_e820;
+
+       if (!is_initial_xendomain())
+               return 0;
+       for (i = 0; i < machine_e820.nr_map; i++) {
+               const struct e820entry *ei = &machine_e820.map[i];
+#endif
+
                if (type && ei->type != type) 
                        continue;
                if (ei->addr >= end || ei->addr + ei->size <= start)
@@ -116,7 +126,7 @@ int __meminit e820_any_mapped(unsigned l
        } 
        return 0;
 }
-#endif
+EXPORT_SYMBOL_GPL(e820_any_mapped);
 
 /*
  * This function checks if the entire range <start,end> is mapped with type.
Index: sle10sp1-2007-03-28/drivers/char/agp/amd64-agp.c
===================================================================
--- sle10sp1-2007-03-28.orig/drivers/char/agp/amd64-agp.c       2007-04-04 
17:07:13.000000000 +0200
+++ sle10sp1-2007-03-28/drivers/char/agp/amd64-agp.c    2007-04-04 
16:45:36.000000000 +0200
@@ -14,6 +14,7 @@
 #include <linux/agp_backend.h>
 #include <linux/mmzone.h>
 #include <asm/page.h>          /* PAGE_SIZE */
+#include <asm/e820.h>
 #include <asm/k8.h>
 #include "agp.h"
 
@@ -252,7 +253,9 @@ static struct agp_bridge_driver amd_8151
 /* Some basic sanity checks for the aperture. */
 static int __devinit aperture_valid(u64 aper, u32 size)
 {
+#ifndef CONFIG_XEN
        u32 pfn, c;
+#endif
        if (aper == 0) {
                printk(KERN_ERR PFX "No aperture\n");
                return 0;
@@ -265,6 +268,7 @@ static int __devinit aperture_valid(u64 
                printk(KERN_ERR PFX "Aperture out of bounds\n");
                return 0;
        }
+#ifndef CONFIG_XEN
        pfn = aper >> PAGE_SHIFT;
        for (c = 0; c < size/PAGE_SIZE; c++) {
                if (!pfn_valid(pfn + c))
@@ -273,6 +277,11 @@ static int __devinit aperture_valid(u64 
                        printk(KERN_ERR PFX "Aperture pointing to RAM\n");
                        return 0;
                }
+#else
+       if (e820_any_mapped(aper, aper + size, E820_RAM)) {
+               printk(KERN_ERR PFX "Aperture pointing to RAM\n");
+               return 0;
+#endif
        }
 
        /* Request the Aperture. This catches cases when someone else
Index: sle10sp1-2007-03-28/include/asm-i386/e820.h
===================================================================
--- sle10sp1-2007-03-28.orig/include/asm-i386/e820.h    2007-04-04 
17:07:13.000000000 +0200
+++ sle10sp1-2007-03-28/include/asm-i386/e820.h 2007-04-04 16:45:36.000000000 
+0200
@@ -38,6 +38,7 @@ extern struct e820map e820;
 
 extern int e820_all_mapped(unsigned long start, unsigned long end,
                           unsigned type);
+extern int e820_any_mapped(u64 start, u64 end, unsigned type);
 
 #endif/*!__ASSEMBLY__*/
 



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